Electronic relay



Sept. 20, 1949.

E. R. MICKLE ELECTRONIC RELAY Filed May 10, 1946 Ihvencor: Edwin R. Mickie,

by H is Attorvfi ey- Patented Sept. 20, 1949 ELECTRONIC RELAY Edwin E. Mickie, Schenectady, N. Y.', assignor to General Electric Company, a corporation of New York Application May 10, 1946, Serial No. 668,835

4 Claims.

This invention relates to electronic relays, and it has for an object the provision of a simple, reliable and improved device-of this character.

Another object of the invention is the provision oia relay which will pick up when a signal voltage decreases from a relatively high value and approaches a relatively lower predetermined value andwhich willdrop out when the signal voltage slight-1y exceeds this predetermined value.

In carrying the invention into effect in one form thereof, the operating coil of an electromagnetic switching device is connected in the anode-cathode circuit of a shield grid type electric valve which is supplied from a suitable source of alternating voltage. A pair of input terminals are provided to which a direct signal voltage is supplied. Across these input terminals is connected a resistor, an intermediate point of which is connected to the cathode of the electric valve. A second resistor is connected from one terminal of the first resistor to the shield grid of the electric valve, and a third resistor is connected between the other terminal of the first resistor and the other grid of the electric valve. In a modification, the cathodes of an additional pair of valves are connected to the intermediate point of the first resistor, and the anodes are respectively connected to the thyratron grids.

For a better and more complete understanding of the invention, reference should now be had to the following specification and to the accompanying drawing of which Fig. 1 is a simple diagrammatical sketch of an embodiment of the invention, and Fig. 2 is amodiflcation.

Referring now to the drawing, the operating coil 1 of an electromagnetic switching device is connected in the anode-cathode circuit of a suitable electric valve such as the thyratron 2. Within the envelope of thethyratron is contained an ionizable medium such as mercury vapor or argon. As shown, the thyratron is provided with an anode 2a, a cathode 2b, a control grid 20 and a shield grid 2d. Alternating voltage is supplied to the anode-cathode circuit from the secondary Winding 3a of a transformer 3 of which the primary winding 31) is connected to a suitable source of alternating voltagewhich is represented by the two supply conductorsl.

A pair of input signal voltage conductors 5 and 6 are provided. A resistor 'I is connected across "to. input conductors 5 and '6. It is shown as comprising :two approximately equal sections la and lb. Between the outside terminal of resistor section .la' and the shield grid id is connected a resistor 8, and a similar and approximately equal resistor 9 is connected between the outside terminal of resistor section lb and the control grid. 20.

A connection 10 is provided 'between the cathode 2b of the thyratron and an intermediate point on the resistor 1.

The anodes i la and l2a of two diode valves H and 52 are respectively connected to the shield grid 2d and control grid 20 of the thyratron 2 and the cathodes [lb and l2b of these valves are connected to the cathode 2b of the thyratron which is connected to the approximate midpoint of the resistor l. The two valves Hand l2 are preferably contained within a common envelope.

With the foregoing understanding of the elements and their organization, the operation of the relay will readily be understood from :the following description.

It may he assumed that the predetermined value of voltage at which the switching device is to be picked up is a low voltage near zero volts, and that it is to drop Olllt when the signal Voltage increases slightly above this predetermined voltage.

A signal voltage of substantial magnitude is supplied to the input terminals 5 and 6. It is assumed that the polarity of this voltage is such that the terminal 5 is positive and the terminal 5 is negative. The shield grid 2d is therefore positive and the control grid 20 is negative with respect to the cathode. However, the control grid is more negative with respect to the cathode than the shield grid is positive owing to the voltage drops in resistors 8 and lb.

Since :terminal 5 is positive with respect to terminal t, a current flows through resist-or 8 and from the upper terminal of resistor 8 through rectifier II and from the shield grid 201 to the cathode 2b in parallel and then through resistor lb to the terminal 6. The high value of the resistor 8 together with the shunting effect of rectifier H results in a current flow from shield grid 2d to cathode, which is very minute and not sufiicient to cause conduction. The potential of the shield grid 20! is maintained between zero and a very low positive voltage throughout a wide range of signal voltages which are positive at the terminal 5. The control grid 20 assumes the full negativepotential of the voltage between terminal 6 and point i because no current flows through resistor 9.

I;f the signal voltage decreases, the negative potential of terminal 6 with respect to point I, which is the voltage of the controlggrid 2,0 with respect to the'cathode '2b, is correspondingly de creased. Also the voltage of terminal 5, which is positive with respect to point I, is correspondingly reduced. However, owing to the rectifier action of valve I l, the voltage of the shield grid 2:2 with respect to point 1 decreases only slightly with a decrease in voltage of terminal 5. The negative voltage of the control grid, however, decreases with the signal voltage and finally the predetermined low value is reached at which the thyratron becomes conducting. As a result the operating coil l is energized and the movable core member is picked up.

On the other hand, if the signal voltage increases slightly above the predetermined value, the thyratron will revert to a non-conducting condition and the relay will drop out.

If the polarity of the signal voltage is reversed, the operation is similar. In this connection assume that the polarity of the signal voltage is positive at the terminal 6 and negative at terminal 5.

Since the voltage of the terminal 6 is positive with respect to terminal 5, a current flows through resistor 9 and from the upper terminal of resistor 9 through the rectifier valve I2 and the control grid 20 to cathode 2b in parallel. Owing to the high ohmic value of resistor 9, together with the shunting effect of the rectifier 12, the current which fiows from the control grid 20 to cathode 2b is very minute and is not sufiicient to cause conduction between anode and cathode. The actual voltage of the control grid 20 with respect to the cathode 2b is maintained between zero and a very small positive potential throughout a wide range of signal voltages applied to terminals z and 6. The shield grid 2d assumes the full negative voltage between terminal '6 and point 1 because no current flows through resist-or 8.

As the signal voltage decreases, the negative voltage of terminal 5 with respect to point 1, which is the voltage of the shield grid 2d with respect to cathode 2b, decreases correspondingly, Also the voltage of terminal 6, which is positive with respect to point I, is correspondingly reduced. However, owing to the rectifier action of valve l2, the positive voltage of the control grid 20 with respect to point 1 and cathode 2b, decreases only slightly with a decrease in the positive voltage of terminal 6. The negative voltage of the shield grid 2d, however, decreases with the signal voltage until finally the predetermined low value is reached at which the thyratron becomes conducting.

A slight increase in the signal voltage makes the shield grid sufficiently negative with respect to the cathode to cause the thyratron to cease conducting and drop out the relay.

In the modification of Fig. 2 the resistor i of the Fig. l modification is replaced by a potentiometer is which is provided with a slider I 3a to which the cathodes of the diode valves M and [5 are connected. As shown the cathode of the thyratron I6 is heated by a filamentary heating element l6a which is supplied from a secondary winding lie of the supply transformer [1. The slider [3a is connected to the free terminal of the heating element so that the voltage of the filament is inserted between the cathode of the thyratron and the slider |3a so that it acts as a hold off bias on both grids. By adjustment of the potentiometer the pick-u and drop-out values may be equalized irrespective of the polarity of the signal voltage. The insertion of the heater voltage in circuit with the cathode of the thyratron make it possible to decrease the pickup and drop-out value of the relay to a very low value, i. e. approximately to zero volts.

The operation is the same as the operation of the modification of Fig. 1.

Examples of tubes, resistors and circuit values which will give very satisfactory operation are set forth in the following table:

Valve 2, valve i6GL2051 shield grid thyratron Valves l I and l 26x5 rectifier Resistors 8 and 9100,000 ohms Resistors la and lb-25,000 ohms Voltage of secondar winding 3a250 volts R. M. S.

Potentiometer l350,000 ohms Valves [8 and l9-CD5006 glow tubes Signal voltage at terminals Lit-Variable over wide range, e. g. 250 volts-0 volts Although in accordance with the provisions of the patent statutes this invention is described as embodied in concrete form and the principle thereof has been explained together with the best mode in which it is now contemplated applying that principle, it will be understood that the elements shown and described are merely illustrative and that the invention is not limited thereto since alterations and modifications will readily suggest themselves to persons skilled in the art without departing from the true spirit of this invention or from the scope of the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric valve control system comprising in combination an electric valve containing an ionizable medium and provided with anode, cathode, control grid and shield grid, means for supplying an alternating voltage to said anode and cathode, a pair of input signal voltage conductors, a resistor connected across said conductors, a connection from the approximate middle point of said resistor to said cathode, a second resistor connected between one terminal of said first resistor and said shield grid, and a third resistor substantially equal to said second resistor connected between the other terminal of said first resistor and said control grid.

2. An electric valve control system comprising in combination an electric valve containing an ionizable medium and provided with anode, cathode, control grid and shield grid, means for supplying an alternating voltage to said anode and cathode, a pair of input signal voltage conductors, a resistor connected across said conductors, a connection from the approximate middle point of said resistor to said cathode, a second resistor connected between one terminal of said first resistor and said shield grid, a third resistor substantially equal to said second resistor connected between the other terminal of said first resistor and said control grid, and a pair of diode rectifier electric valves each having a cathode connected to said middle point of said first resistor and one of said pair of valves having an anode connected to one of said grids and the other having an anode connected to the other of said grids.

3. An electric valve control system comprising in combination an electric valve containing an ionizable medium and provided with anode, cathode, control grid and shield grid, means for supplying an alternating voltage to said anode and cathode, a pair of input signal voltage conductors, a potentiometer connected across said conductors, said potentiometer having a slider, a connection from said slider to said cathode, a first resistor connected between one terminal of said potentiometer and one of said grids, a second resistor Substantially equal to said first resistor connected between the other terminal of said potentiometer and the other of said grids, and a pair of electric valves each having a cathode connected to said slider, and one of said pair of valves having an anode connected to one of said grids, and the other having an anode connected to the other of said grids.

An electric valve control system comprising in combination an electric valve containing an ionizable medium and provided with an anode, a cathode, a control grid and a shield grid, said cathode being provided with a heating element, means for supplying an alternating voltage to said anode and cathode, a pair of input signal voltage conductors, a potentiometer connected across said conductors and provided with a sliding contact,

a resistor connected between one terminal of said 20 potentiometer and one of said grids, a second resistor connected between the other terminal of said potentiometer and the other of said grids, a connection between said sliding contact and said cathode, means for supplying a voltage to said heating element, and connections for supplying said voltage in circuit between said cathode and said sliding contact to bias said grids negatively with respect to said cathode.

EDWIN R. MICKIE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,383,600 Grosdoif Aug. 28, 1945 2,428,126 Nicholson Sept. 30, 1947 

